Experimental Study of the Cup-Flame Gas-Burning Installation of Swirl Flow

The cup-flame burning installation with swirl-flow of natural gas is a new type device with high performance. It possesses the characteristics of fast speed heating up, homogeneous heating, fuel conservation and novel structure. It can be widely used for forging furnaces, heat treatment hardening furnaces, low fusing point melting furnaces and some other kinds of kilns. This installation is one with promising prospect.     

工业循环冷却水余能利用及其关键技术

基于工业循环冷却水系统构成方式的研究,归纳出了3种典型的循环水系统:冷热水串联系统、冷热水独立系统和循环水回水开敞式系统.通过对循环冷却水系统中剩余能量的分析发现:无论构成方式如何,其系统余能一般在5~30 m左右,少数可达到50 m左右,都属中低水头余能系统.根据循环冷却水余能特点,提出了3种典型的余能利用方式:水轮-风机组余能利用方式、小型或微型水轮发电装置向外送电的余能利用方式和透平泵余能利用方式.针对3种余能利用方式,指出了各自的关键技术或存在的问题:水轮-风机组的关键是超低比转数水轮机的设计,但其成本较高、效率较低、机型单一,现缺乏对超低比转数水轮机内部流场的研究;余能发电的关键在于水轮机的选型及其循环水的保护和发电机逆功率保护;透平泵的关键是水轮机或者反转水泵的设计,并且水泵反转作水力透平在工作过程、设计理论与方法、流道型式等方面与水轮机存在很大差异.因此,透平泵中透平部分是选反转水泵、水轮机,还是水泵水轮机,应经过经济技术比较才能确定.     

Inheritance of characters determining growth and development of tomato (Lycopersicon esculentum Mill.) under low energy conditions

Summary Diallel crosses were made between 15 tomato genotypes with varying performance under a low energy regime. It appeared that differences between genotypes for 11 vegetative and generative plant characters are determined mainly by additive genetic variation. For breeding cultivars adapted to low energy conditions, crossing genotypes with a high GCA for weight of trusses and fruits (WTF) and genotypes with a high GCA for weight of vegetative plant parts (WVP) seems most promising. Complications may arise from the negative correlation between GCA values for WTF and WVP, and the strong positive correlation between GCA values for fruit number and WTF, causing small fruits.     

THE THEOREM OF STATIONARY VALUE OF WEIGHTED ENERGY AND ITS WEIGHTING FUNCTIONS

This paper presents two energy functionals which are made as stationary values. Thus, the theorem of stationary value of weighted generalized potential energy and the theorem of stationary value of weighted generalized complementary energy are established. In the first theorem, the stress boundary weighting function must be equal to the internal weighting function while the displacement boundary weighting function is independen; and in the (?)econd theorem, the displacement boundary weighting function must be equal to the internal weighting function while the stress boundary weighting function is independent.     

Analysis of the uncertainty associated with the estimation of nitrogen losses from farming systems

This work describes the analysis of the uncertainty linked to the annual direct and indirect losses of different nitrogenous compounds at the scale of a group of farms. The nitrogen (N) forms taken into account are: ammonia (NH₃), nitric oxide (NO), nitrous oxide (N₂O), dinitrogen (N₂) and nitrate (NO₃). The gaseous N emissions for the different components of the farms are estimated with a selection of adapted emission factors. The NO₃ losses at the farm scale are calculated as the difference between the surplus of the farm-gate N balance and the gaseous N emissions.     

Comparative assessment of five methods of determining sap flow in peach trees

Five different methods of determining sap flow (SF), three based on heat pulse (compensation heat pulse, New Zealand—cHP–NZ; compensation heat pulse, Greenspan/Australia—cHP–G (South oriented), and cHP–G–EW (East and West oriented, average); non-compensation heat pulse, Ariel/Israel—ncHP), one based on stem heat balance (Dynamax/USA—SHB), and another based on heat dissipation (Granier/France—HD) were compared in an experiment performed on peach trees in Northeast Spain. Two irrigation treatments (drip-irrigated) were applied: a control and a stress treatment, the latter consisting of withholding water from day 190 to 199. Between 1 and 3 different systems were installed in some trees of both, the control and stress treatments. All the techniques reflected the evolution of water stress in the stressed trees with a very similar tendency and in agreement with the evolution of predawn water potential (Ψp). Ψp correlated well with sap flow (SF) determined with all the systems (r² > 0.65) in the stress treatment, indicating that all the SF techniques detected changes in tree water status. The cHP–NZ system was the first to detect a SF reduction through the outer xylem vessels, as a response to water withholding. In control trees, daily SF rates provided by the three heat pulse and heat balance methods were well correlated with ETo and somewhat less with global radiation; all regressions improved on an hourly basis. Daily pattern and magnitude of mean SF rates monitored by the three heat pulse systems were quite similar in control trees. This was reflected by high regression coefficients when compared with each other. Higher SF rates recorded by ncHP methods in comparison with cHP–G and cHP–NZ might be attributed to technical limitations and to different sensor orientation. In an accompanying experiment, substantial differences between East and West location of the cHP–G sensors were observed, but when taking the mean value of those daily SF rates, differences between ncHP and cHP–G–EW were lower. Mean monthly crop coefficients, calculated by using SF data computed with ncHP method and soil evaporation as determined with microlysimeters, were 0.64 in July and 0.67 in August. SF systems can be used to detect plant water stress related to control, and might be useful for irrigation scheduling based on plant water status. The SF techniques analysed showed potential to better determine actual plant water necessities than other traditional methods, but a preceding calibration is needed.     

Vineyard evaporative fraction based on eddy covariance in an arid desert region of Northwest China

Studying farmland evaporative fraction (EF) plays an important role in interpreting the components of energy budget and evapotranspiration (ET). The present study examines the pattern of vineyard EF after monitoring energy components by eddy covariance for 2 years, and estimates the crop ET by EF in the arid desert region of Northwest China. Main results indicate that EF during daytime is nearly constant on sunny days when the available energy exceeds 200 W m⁻², but EF becomes relatively unsteady when the available energy is lower than 200 W m⁻². Furthermore, daytime average EF is relatively low in the early growth stage, nearly constant in the mid-later stage, and significantly reduced in the later stage; Moreover, mean EF in different periods of daytime is in good agreement with daytime average EF, mean EF during 10:00–15:00 h is relatively close to daytime average EF and mean EF during 14:00–15:00 h is approximately equal to daytime average EF. The estimated daytime ET from mean EF during 14:00–15:00 h is highly correlated to the measured ET by Bowen ratio-energy balance though the value is partially underestimated. This study demonstrated that daytime ET can be estimated from midday EF and the relationship can be used to guide irrigation practice in the arid region.     

Representation of rainfed valley ricefields using a soil-water balance model

Soil-water conditions for ricefields located in valleys in micro-catchments are simulated using a daily soil-water balance model. The crop is primarily rainfed but there is also limited irrigation water. The simulation covers a complete year and includes features such as rainfall, irrigation releases, runoff from uplands, actual evaporation and evapotranspiration, percolation losses through the bed and bunds of the ricefield, standing water in the field and overflows from the ricefield. A specific location in Sri Lanka is selected to illustrate the approach. The impacts of different conditions are explored including alternative irrigation releases, increased losses through the bed and bunds of the ricefield and a lower overflow from the ricefield. Simulations indicate that ricefields which are towards the valley sides have an increased inflow due to runoff from adjacent uplands; this can lead to improved rice yields. However, reducing heights of the bunds to half the original value results in substantial overflows during periods of high rainfall while the number of days without submergence almost doubles. This uncomplicated model is consistent with the limited field data and information available; it provides a realistic representation of the important processes and indicates why poor crop yields often occur.     

A discussion on and alternative to the Penman-Monteith equation

The Penman-Monteith (PMe) equation that estimates evaporation from leaf/canopy surfaces is based on a few approximations. Several authors discussed ensuing errors and suggested improvements. This paper reminds those discussions which ended in the early nineties. It compares linearized PMe− with non-linear iterative solutions and illustrates resulting deviations. It differentiates between deviations for daily and hourly evaporation rate estimates. The latter are found to be higher. It also demonstrates deviations obtained at two different altitudes above sea level. Considering present tendencies to refine evaporation estimates for practical purposes and making use of easily available methods for solving non-linear equations this paper offers a new method to estimate evaporation.In a first step, a simple algebraic term, the surface temperature control sum, is introduced to find approximate differences between air and evaporating surface (leaf, canopy) temperatures. It suggests to concentrate research on the r_s/r_a ratio. A new formula is derived for estimating leaf/canopy surface temperatures for non-water stressed plants.In a second step, the estimates of temperature differences are used to calculate evaporation estimates. This two-step approximation leads to appreciably smaller errors as compared to the PMe-solution over the full range of input parameters of agro-meteorological relevance. It is, however, less accurate than some of methods proposed in literature. The method is meant for practical application in agricultural water management.     

Estimation of irrigation return flow from paddy fields considering the soil moisture

The objective of this study was to estimate irrigation return flow in irrigated paddy fields considering the soil moisture. The proposed model was applied to examine its feasibility with regard to the growing period of rice. Simulation results showed a good agreement between the observed and simulated values: root mean square error (RMSE) of 6.05-7.27 mm day⁻¹, coefficient of determination (R²) of 0.72-0.73, and coefficient of efficiency (E) of 0.54-0.55. The estimated average annual irrigation return flow during the period from 1998 to 2001 was 306.2 mm, which was approximately 25.7% of the annual irrigation amounts. Of this annual irrigation return flow, 14.1% was attributable to quick and 11.6% to delayed return flow. These results indicate that considerable amounts of irrigation water in the paddy fields were returned to streams and canals by surface runoff and groundwater discharge. The modeling assessment method proposed in this study can be used to manage agriculture water and estimate irrigation return flow under different hydrological and water management conditions.